Reversing switch



Feb. 4, 1969 M. P. SCHLIENGER REVERS ING SWITCH Filed March 13, 1967 INVENTOR.

lownsend lownsend Feb. 4, 1969 M. P. SCHLIENGER REVERSING SWITCH Filed March 15, 1967 Sheet fiqi.

MAX P SCHLIENGER INVENTOR.

/ownsend lown'send United States Patent 3,426,167 REVERSING SWITCH Max P. Schlienger, 19 Rollingwood Drive, San Rafael, Calif. 94101 Filed Mar. 13, 1967, Ser. No. 622,516 US. Cl. 20082 13 Claims Int. Cl. H01h 35/38 ABSTRACT OF THE DISCLOSURE A reversing switch having four spaced, generally parallel, electrodes, two of which are to be coupled to a source of electrical power and the other two adapted to be coupled to an electricallyactuated device. First and second pairs of electrical contact shoes are disposed to bridge respective electrodes in a manner such that the polarities-of the electrodes to be connected to the electrically actuated device can be reversed by merely shifting one pair of shoes out of engagement with respective electrodes as the other pair of shoes is shifted into engagement with respective electrodes. Selectively actuated drive means effect the movement of the shoes.

This invention relates to heavy duty, industrial type switches capable of carrying relatively large electrical currents. A particular use of the switch of the inventionis in the operation of metal purification apparatus wherein a metal to be purified is deposited in a crucible after an arc is established between the crucible and the electrode of which the metal forms a part. Relatively high values of electrical current are required to establish and maintain the arc and it is oftentimes necessary to reverse the polarities of the crucible and electrode for particular types of metals to be purified. The switch of the present invention is constructed to readily carry out this polarity reversing function without causing arcing of the contacts while, at the same time, the switch is simple and rugged, relatively small in size, and inexpensive to manufacture.

Prior reversing switches suitable for this type of opera tion have a number of disadvantages which the switch of the present invention overcomes. Generally, the prior switches are large in size and complicated in construction. They also are bulky and require a relatively large amount of space. In view of its large size, a typical conventional reversing switch requires a large amount of copper for the electrodes and this increases the overall expense of producing and maintaining the switch. Typical of such a switch is the type shown in US. Patent No. 3,200,219 wherein pivoted contact bars are relied upon for making electrical contact and effecting the reversing action of the switch. By using a pivotal mount for the contacting or bridging members, certain portions of the members approach the electrode before other portions and undesirable arcing may occur, resulting in galling of the electrode and contact members. Moreover, pivotal mounting of the contact members presents bearing problems which require maintenance of the pivot joint at predetermined intervals.

The present invention is directed to a reversing switch which overcomes the problems associated with conventional, heavy duty reversing switches. To this end, the invention includes four electrodes, two of which are to be operably coupled to a source of electrical power and the other two are to be coupled to an electrically actuated device. The electrodes are arranged in a rectangular array to minimize space requirements and to keep to a minimum the amount and thereby the cost of the conductive material used in the various components of the switch. The bridging bars or shoes are shaped to assure a sufiicient area of contact at all times and these components are 3,426,167 Patented Feb. 4, 1969 shifted in a manner to assure that they will quickly and cleanly make and break the necessary electrical contacts without arcing. Thus, the possibility of damage to the switch components is substantially minimized or es sentially eliminated.

The bridging bars or electrical contact shoes are movable along rectilinear paths to overcome the problems associated with pivotally mounting the contact members of conventional switches. Also, by utilizing rectilinear motion, all electrode engaging portions of a contact shoe move uniformly into and out of engagement with an electrode.

Positive electrical contact is further assured by providing each electrical contact shoe with a pair of spaced concavities which are complemental to the convex outer surface of the pair of cylindrical electrodes to be engaged thereby. Thus, a greater area of the contact member engages each electrode. The feature becomes extremely important when relatively large electrical currents pass through the switch.

Hydraulic actuating structure, which is selectively controlled from a remote point, is used for shifting each shoe in opposed directions. Thus, a single pressurized fluid source and suitable valve structure can be relied upon to effect the simultaneous movement of one pair of shoes into electrical contact with respective electrodes as the other pair of shoes is simultaneously moved. out of electrical contact with their electrodes. In this way, there can be no electrical short circuiting of the electrodes and reversing the polarities of the electrodes can be accomplished without structural damage due to arcing.

It is, therefore, the primary object of this invention to provide a heavy duty electrical reversing switch which is simple, rugged and inexpensive in construction, requires only a minimum of space, and provides for positive electrical contact between electrodes without appreciable arcing.

A further object of the invention is to provide a reversing switch of the type described which utilizes electrically conductive bridging shoes which move along rectilinear paths rather than along arcuate paths to assure uniformity in electrical contact of all portions of the shoes and to substantially eliminate any bearing problems associated with a pivotal mounting.

A feature and advantage of the present reversing switch is that the electrical contact members can be immediately connected and disconnected from the respective electrodes. This is accomplished by the arrangement of the electrodes as well as the construction of the shoes themselves and the 'way' in which the shoes move. A minimum of arcing can occur with the construction of the present invention so that damage to the electrodes or the contact members, leading to galling or the like, is kept to a minimum.

Another feature and advantage of the present invention is that the contact shoes are in the form of rigid bars or straps and provided with concavities which are complemental to the external configurations of respective electrodes. Thus, a greater area of the contact members is utilized for engaging the electrodes to thereby assure a better path for the relatively high electrical currents to which the electrodes are subjected.

Still a further feature and advantage of the invention is that the electrodes are columnar in construction and arranged in a rectangular array, with the electrodes at respective corners of the array. By means of this construction, the shoes can be made to traverse rectilinear paths and one pair of shoes can be at one longitudinal location with respect to the electrodes while another pair of shoes can be at a second location along the length of the electrodes. Space, therefore, becomes no problem and the desired reversing effects can be achieved even though the shoes move a relatively short distance with respect to the adjacent electrodes.

Still a further feature and advantage of the invention is that the electrical contacts shoes which are out of engagement with electrodes are at a floating electrical potential so that, even if these shoes are relatively close to the adjacent electrodes, there will be no arcing between the shoes and the electrode. Thus, this feature offsets damage to the metallic structures of the switch due to arcing to thereby increase the operating life of the switch.

Another feature and advantage of this invention is that each shoe is made up of two rigid straps which move simultaneously in opposite directions. Thus, the sections can be caused to clamp against respective electrodes to thereby assure a more positive contact while, at the same time, the clamping action assures that the contact will be maintained until the sections are shifted away from each other.

In the drawings:

FIG. 1 is a perspective view, partly in section, of the reversing switch;

FIG. 2 is a schematic view of the switch in combination with the hydraulic drive means for each of the electrical contact shoes of the switch;

FIG. 3A is a side elevational view of the drive structure for one of the shoes, showing the shoe out of electrical contact with a respective electrode; and

FIG. 3B is a view similar to FIG. 3A but illustrating the shoe in electrical contact with an adjacent electrode.

A preferred embodiment of the switch is broadly denoted by the numeral and is illustrated in FIG. 1. Switch' 10 includes a first pair of tubular, cylindrical electrodes 12 and 14 and a second pair of tubular, cylindrical electrodes 16 and 18. Electrodes 12 and 14 are adapted to be coupled to a source of direct current and, to this end, they are provided with conventional lugs 20 and 22 respectively. The lugs are secured in any suitable manner to the extremities of respective electrodes and a lead 24 extends outwardly from each lug, respectively. These leads are adapted to be coupled to the DC power source which, of course, will be polarized. Thus, one of the first pair of electrodes will thereby be electrically positive while the other electrode will be electrically negative.

Electrodes 12, 14, 16 and 18 are arranged in a sub stantially rectangular array with the electrodes disposed at respective corners of the array. To this end, the electrodes are mounted in three spaced panels 26, 28 and 30 formed of insulating material having a relatively high dielectric constant. The panels are maintained in generally parallel spaced relationship from each other by spacers 32 and 34. The panels have openings therethrough for receiving the electrodes and the latter are disposed substantially parallel to each other.

Each of the electrodes is adapted to be water cooled and this is necessary because of the relatively high values of electrical current to which the electrodes are subjected. Each electrode, therefore, has an inlet opening at one end and an outlet opening at the opposite end. A pair of pipes 36 communicate with the ends of each electrode and these pipes are adapted to be operably coupled to a source of coolant, such as a water source.

The second pair of electrodes 16 and 18 are provided with lugs 38 and 40, respectively, which are substantially identical to lugs 20 and 22. A lead 42 extends outwardly from each of the lugs 38 and 40, respectively, leads 42 being adapted to couple lugs 38 and 40 to an electrically actuated device. The primary purpose of switch 10 is to be able to reverse the polarities of electrodes 16 and 18- and this is accomplished through the use of first and second pairs of electrical contact shoes or structures 44 and 46, respectively. The first pair of shoes 44 is disposed at a first location along the lengths of the electrodes; whereas, shoes 46 are disposed at a second location along the electrodes. As shown in FIG. 1, shoes 44 can conveniently be positioned between panels 28 and 30 and shoes 46 can be located between panels 26 and 28. By positioning shoes 44 at a different location from shoes 46, there will be no interference of the shoes at one location with those at the other location. Also, space requirements are kept to a minimum, and the shoes can be relatively wide to assure a more positive electrical contact even though the overall dimensions of switch 10 are kept to a minimum.

Each of the shoes 44 and 46 includes a pair of rigid bars or straps 48 and 50 mounted on opposed sides of a respective pair of electrodes. Bars 48 and 50 of each shoe are simultaneously movable in opposite directions so that, when electrical contact is to be made with respective electrodes, the bars move toward each other and clamp onto the electrodes in the manner shown in FIG. 3B. As shown in FIG. 1, shoes 46 are in clamping relationship to respective electrodes. Conversely, the bars of each shoe move away from each other when electrical contact is to be interrupted.

Bars 48 and 50 of each shoe may be mounted in any suitable manner for reciprocation with respect to adjacent electrodes. For purposes of illustration only, the mounting structure for the bars of each shoe is shown in FIGS. 3A and 313 wherein each bar 48 is connected to a central shaft 52 extending through a sleeve 54 rigidly connected to the corresponding bar 50. Shaft 52 and sleeve 54 are received within and are shiftable relative to a cylinder 56 having a pair of spring-biased pistons 58 and 60 therewithin. Pistons 58 and 60 of each shoe 44 are separated by a space 62 which communicates by means of a conduit 64 to a fluid valve 66, the latter in turn being coupled to a tank 68 containing a fluid under pressure. Each shoe has its own piston and cylinder assembly for reciprocating the corresponding straps 48 and 50, the piston and cylinder assemblies providing power sources for driving the various shoes.

FIGS. 3A and 3B illustrate that the same pressurized fluid source can be utilized to actuate shoes 44 and 46. In these two figures, only one shoe 44 and one shoe 46 are shown, but it is to be made clear that cylinders 56 corresponding to shoes 44 are in parallel relationship while cylinders 56 of shoes 46 are in the same relationship. Thus, valve 66 simultaneously actuates both pairs of shoes 44 and 46' and this can be accomplished by an operator selectively manipulating a lever 70 operably coupled to the movable valve member 72 of valve 66. Valve 66 and tank 68 form a unit 74 shown schematically in FIG. 2.

Each of the straps 48 and 50 of each shoe has a pair of spaced concavities 76 and 78, substantially complemental to the convex outer surface of the corresponding electrode. When the shoes engage the adjacent electrodes, the latter are partially received within the concavities.

This feature increases the effective area of electrical contact. Also, FIG. 1 shows the use of widthwise teeth 80 in each concavity which bite into the adjacent electrode and enhance the electrical contact.

The electrodes of switch 10 are preferably formed from a good electrical conductor, such as copper. Similarly, straps 48 and 50 of each shoe can also be for-med from the same material as the electrodes or from different materials. Any suitable insulating material can be utilized to form panels 26, 28 and 30. For instance, these panels can be formed from Panelyte which is an asbestos derivative commercialized by Thiocol Chemical Company, Houston, Texas. This material has a relatively high di electric constant so as to prevent electrical current flow through the panels and between adjacent pairs of electrodes.

Operation Electrodes 12 and 14 are coupled to a DC voltage source by leads 24 after electrodes 16 and 18 have been connected by leads 42 to an electrically actuated device.

A suitable master ON-OFF switch will generally be coupled to one of the leads 24 so that, before the shoes are to be shifted, power can be removed from electrodes 12 and 14. The master switch can be closed after the shoes have been shifted to again connect electrodes 12 and 14 to the power source. This .arrangement prevents arcing during the shifting of the shoes. For purposes of illustration, it is assumed that electrodes 16 and 18 are to be made positive and negative respectively. This will require that shoes 44 be moved into electrical contact with respective electrodes as shown in FIG. 2. Shoes 46 will thereby be out of contact with their respective electrodes for this condition to exist.

Assuming also that shoes 46 are initially in contact with their electrodes, lever 70 is swung to the dashed line position of FIG. 3A to cause valve member 72 to shift to the left.

When this occurs, conduits 88 become connected to the return conduit 98 and fluid pressure within the corresponding cylinders 56 will rapidly decrease, causing bars 48 and 50 of each shoe 46 to separate and move out of engagement with respective electrodes. The movement of valve member 72 .also causes conduits 64 to become connected to the pressure conduit 96, whereby fluid pressure in cylinders 56 corresponding to shoes 44 will increase to cause the corresponding bars 48 and 50 to move toward each other and thereby clamp onto their electrodes.

When it is again desired to reverse the polarity of the device, lever 70 is shifted back to the full line position of FIG. 3A to move valve member 72 to the right. This action connects each conduit 64 to return conduit 90 and connects each conduit 88 to a pressure conduit 86. Fluid pressures in the various cylinders change so that shoes 44 move out of engagement with their electrodes and thereafter shoes 46 move into engagement with their electrodes. Thus, electrode 16 will have the polarity of electrode 14 and electrode 18 will have the polarity of electrode 12.

During the use of switch 10, a coolant, such as water, will be flowing through each electrode to cool the same. Conventional equipment can be used for this purpose.

When either pair of shoes are out of engagement with corresponding electrodes, the shoes will be at a floating potential so that the danger of arcing is substantially eliminated and thereby no damage can be caused to the electrodes or the shoes due to an arc. The relatively wide bars which form the various shoes provide sufiicient area to assure positive electrical contact with the various electrodes. The teeth on the bars also assure good contact because of the way in which they bite into the electrode surfaces. The concavities assure a greater area of contact and allow for uniformity of contact throughout the arcuate length of the concavity.

The columnar arrangement of the electrodes positions one pair of shoes at a different longitudinal location than the other pair of shoes to eliminate any interference between the shoes when the latter are shifted. This arrangement also permits electrical contact easily and quickly to be made and to be broken. By arranging the electrodes in a rectangular array, the shoes can be made to move along rectilinear paths rather than be pivoted into contact with the electrodes. This assures more uniform contact and avoids bearing problems.

Switch is constructed so as to occupy a minimum space and to be relatively inexpensive while at the same time, it is able to be used with high electrical currents in the same manner as conventional reversing switches which are quite expensive to produce and are large and complex in construction.

What is claimed:

1. A reversing switch comprising: a pair of first electrodes adapted to be connected to a source of electrical power; a pair of second electrodes adapted to be connected to an electrically actuated device; -a pair of first contact structures, one of said first structures being mounted for movement into .and out of electrical contact with one of said first electrodes and one of said second electrodes, the other of said first structures being mounted for movement into and out of electrical contact with the other of said first electrodes and the other of said second electrodes; a pair of second contact structures, one of said second structures being mounted for movement into and out of electrical contact with said one first electrode and said other second electrode, the other of said second structures being mounted for movement into and out of electrical contact with said other first electrode and said one second electrode; and means coupled with said structures for alternately moving said pairs of structures into electrical contact with respective electrodes, whereby each second electrode is alternately connected to said first electrodes.

2. A reversing switch comprising: a pair of first columnar electrodes and a pair of second columnar electrodes, said electrodes being arranged in a rectangular array with each electrode being disposed at a respective corner of the array; a first pair of electrical contact shoes at a first location along the length of said electrodes and a second pair of electrical shoes at a second location along the length of said electrodes, one shoe of said first pair being movable into and out of engagement with one of said first electrodes and one of said second electrodes, the other shoe of said first pair being movable into and out of engagement with the other of said first electrodes and the other of said second electrodes, one shoe of said second pair being movable into and out of engagement with said one first electrode and said other second electrode, the other shoe of said second pair being movable into and out of engagement with said other first electrode and said one second electrode; first actuatable drive structure for simultaneously moving said first pair of shoes into and out of engagement with respective electrodes; second actuatable drive structure for simultaneously moving said second pair of shoes into and out of engagement with respective electrodes; and means cou pled with said drive structures for alternately actuating the same to thereby alternately connect each second electrode to said first electrodes.

3. A reversing switch comprising: first and second pairs of elongated, generally parallel electrodes, each electrode having a convex outer surface; first and second pairs of electrical contact shoes, each shoe having a pair of spaced electrode-receiving concavities extending longitudinally of said electrodes and being substantially complemental to said outer surfaces of a respective pair of electrodes, one shoe of said first pair being movable into and out of engagement with one of said first pair of electrodes and one of said second pair of electrodes, the other shoe of said first pair being movable into and out of engagement with the other of said first pair of electrodes and the other of said second pair of electrodes, one shoe of said second pair being movable into and out of engagement with said one of said first pair of electrodes and said other of said second pair of electrodes, the other shoe of said second pair being movable into and out of engagement with said other of said first pair of electrodes and said one of said second pair of electrodes; and means coupled with said shoes for alternately moving said first and second pairs of shoes into engagement with respective electrodes, whereby each of said second pair of electrodes is alternately connected to the electrodes of said first pair of electrodes.

4. A reversing switch as set forth in claim 3 wherein said electrodes are cylindrical.

5. A reversing switch as set forth in claim 3 wherein each electrode is cylindrical, each shoe including a pair of bars disposed on opposed sides of respective electrodes, each bar having a pair of spaced, electrode-receiving concavities, said moving means including structure for simultaneously moving the sections on each pair toward and away from respective electrodes.

6. A reversing switch comprising: a pair of spaced, first electrical conductors generally disposed in a common plane and adapted to be coupled to an electrical, current-receiving device; a pair of spaced, second electrical conductors adapted to be coupled to a source of electrical power, each of said second conductors being on opposed sides of said common plane and adjacent to and spaced from said first conductors; a pair of first electrically conductive shoes, one of said first shoes being mounted for movement into a position bridging one of said first conductors and one of said second conductors, the other first shoe being mounted for movement into a position bridging the other first conductor; a pair of second electrically conductive shoes, one of said second shoes being mounted for movement into a position bridging said one first conductor and said other second conductor, the other second shoe being mounted for movement into a position bridging said other first conductor and said one second conductor, and means coupled with said shoes for alternately moving the first shoes and the second shoes into said positions thereof with the second shoes being out of their positions when the first shoes are in their positions and with the first shoes being out of their positions when the second shoes are in their positions.

7. A reversing switch as set forth in claim 6, wherein said conductors have a cylindrical, tubular configuration, each conductor having means for coupling the same to a coolant source.

8. A reversing switch as set forth in claim 7, wherein each shoe has a pair of spaced concavities for complementally receiving the corresponding conductors.

9. A reversing switch as set forth in claim 7, wherein each shoe comprises a pair of rigid bars disposed on opposed sides of respective conductors, each bar having a pair of spaced concavities for complementally receiving and engaging said respective electrodes, said moving means including structure for shifting the bars toward each other to effect engagement with respective electrodes and away from each other to effect disengagement.

10. A reversing switch as set forth in claim 6, wherein each shoe has a predetermined width and is provided with a pair of spaced concavities extending across the width thereof, there being a number of electrode engaging teeth within each concavity and extending widthwise of the shoe.

11. A reversing switch as set forth in claim 6, wherein is provided a support for said electrodes, said support including a pair of spaced, generally parallel panels of insulating material, said electrodes spanning the distance between and extending into said panels with the electrodes-beinggeuerally parallel with respect to each other.

12. A reversing switch as set forth in claim 6, wherein said moving means includes a fluid actuated power device for each shoe respectively, a source of fluid under pressure, and valve means coupled with said source and said device for directing fluid to the latter from the source to cause the devices of the first shoes to operate in a reverse manner with respect to the devices of the second shoes.

13. A reversing switch as set forth in claim 12, wherein each shoe includes a pair of shiftable bars, each power device including structure for shifting the bars toward each other for engaging respective electrodes and for shifting the bars away from each other for disengaging the electrodes.

References Cited UNITED STATES PATENTS 1,599,232 9/1926 Haight 200 82.1 XR 3,200,219 8/ 1965 Pollak 3351 19 3,296,394 1/1967 COrniellO 20082 FOREIGN PATENTS 568,427 4/ 1945 Great Britain.

ROBERT K. SCHAEFER, Primary Examiner.

H. BURKS, Assistant Examiner. 

